耐候钢及其焊接节点大气腐蚀经时演化预测方法

为了给解决耐候钢桥在应用和发展中所面临的腐蚀问题提供理论方法与对策，针对耐候钢在大气环境中的腐蚀损伤演化特性，通过编制MATLAB程序，建立了基于三维元胞自动机技术的耐候钢焊接节点大气腐蚀经时演化模型。该模型根据耐候钢在大气腐蚀过程中发生的化学反应，将大气腐蚀系统中的关键元素抽象成4种元胞类型，并离散成元胞网格。对母材和焊缝分别定义了不同的元胞邻居类型，模拟了耐候钢焊接节点代表性体元在介观尺度上的腐蚀演化过程，并通过大气暴露试验验证了所提出方法的可行性和有效性，揭示了耐候钢焊接节点腐蚀动力学及蚀坑演化规律，分析了溶解氧浓度和溶解概率对腐蚀损伤的影响。在此基础上提出了耐候钢大气腐蚀经时演化预测方法。研究结果表明：所提出的耐候钢焊接节点经时演化模型稳定可靠，演化规律合理，当时间尺度和空间尺度分别设置为0.2年和100μm时，模拟结果与大气暴露试验数据吻合良好；耐候钢焊接节点的腐蚀损伤主要由溶解概率和溶解氧浓度决定，平均腐蚀深度随溶解概率和溶解氧浓度的增加而增大。所提出的耐候钢大气腐蚀演化预测方法能够较为准确地再现研究对象的大气腐蚀过程，描述和识别研究对象在大气中的腐蚀动力学、腐蚀形态和蚀坑...

Prediction Method of Time-dependent Evolution of Atmospheric Corrosion at Weathering Steel and Its Welded Joints

To provide theoretical methods and countermeasures for solving the corrosion problems faced by weathering steel bridges in the application and development, aimed at the corrosion damage evolution characteristics of weathering steel in the atmospheric environment, an innovative time-dependent evolution model of atmospheric corrosion of weathering steel welded joints, based on the three-dimensional cellular automata technology, is developed using MATLAB. According to the chemical reaction of weathering steel in the atmospheric environment, the key elements in the weathering steel corrosion system are abstracted into four cellular types and divided into cellular grids in the model, and different cellular neighbor types are defined for the base material and the weld respectively, to simulate the corrosion evolution process of the representative volume element of weathering steel welded joints on the mesoscopic scale. The feasibility and effectiveness of the proposed method was verified by the atmospheric exposure tests. Furthermore, the corrosion dynamics and evolution law of corrosion pit of weathering steel welded joints were revealed; the effect of dissolved oxygen concentration and dissolution probability on corrosion damage were analyzed, and the prediction method of long-term corrosion evolution process was raised. The results show that the proposed time-dependent evolution model of weathering steel welded joint is stable and reasonable. When the time scale and lattice spacing are set to 0.2 years and 100 μm, the experimental results show good agreement with the numerical results. The corrosion damage of weathering steel and its welded joints are mainly determined by the dissolution probability and the dissolved oxygen concentration. The average corrosion depth increases with both the dissolution probability and the dissolved oxygen concentration. The proposed time-dependent evolution prediction method of atmospheric corrosion at weathering steel and its welded joints can reproduce the atmospheric corrosion process, describe and identify the corrosion dynamics, corrosion morphology and pit distribution characteristics of the research objects to a large extent, and provide scientific basis for the continuous prediction of corrosion behavior of weathering steel and its welded joints in the long-term atmospheric corrosion process.